In the atomic absorption spectrometry (AAS) it is common to reduce the mercury (Hg) to metal by suitable chemical agents (e.g. sodium hydroboron). The vapor pressure of the mercury at an ambient temperature is already high enough so that the mercury can be passed into a measuring cuvette by a gas flow.
The sensitivity of this method can be considerably increased when the generated mercury vapor is guide through finely distribute metal net (e.g., gold) which metal is then heated. The mercury accumulates at the metal as an amalgan and can be abruptly release by heating so that a higher Hg-density is generated in the measuring cuvette of the spectrometer. Thereby, the sensitivity of the prior devices is increased by approximately factor 10.
Prior devices of this type use a quartz tube with an inner diameter of about 4mm for accommodating the gold net. The gold net is cut to a width of approximately 6mm, and is rolled up and inserted into the quartz tube. The tube with the gold net is arranged in a wire coil which can be electrically heated to approximately 600.degree. C.
When the analysis takes place, the reducing agent is added to the sample, a gas flow is passed through the sample and then through the (cold) quartz tube with the gold net. When the reaction has finished, the quartz tube with the gold net is heated whereby the mercury is abruptly released and is passed into the measuring cuvette.
Now, it is disadvantageous that after the analysis is conducted, a waiting period is needed until the coil, the quartz tube and the gold net have again reached an ambient temperature since a generation of amalgam is only possible at relatively low temperatures.
It is the object of the invention to reduce the length of this waiting period and to provide a faster, better defined temperature increase.